Modifiers or plasticizers are commonly used in polymers to lower the melt viscosity, improve low temperature properties and increase retention of properties at service temperatures. Soft polyolefins, low-molecular weight polyolefins, paraffinic waxes and hydrocarbon-based mineral oils have been used as polyolefin plasticizers with varying degrees of success.
Traditionally, it has been thought that a hydrocarbon plasticizer such as a polyalphaolefin would not have good compatibility with polar or engineering polymers, and, therefore, the hydrocarbon plasticizer would not efficiently modify polar polymers such as nitrile-group containing elastomers. Hydrocarbon-based plasticizers are not typically compatible with nitrile-group containing elastomers, and have a tendency to exude from the polymer composition over time or at elevated temperatures. The loss of plasticizer results in the degradation of the polymer's physical properties, and often leads to premature product failures.
Thus, there is a need for improved polymer compositions comprising a nitrile-group containing elastomer and a non-functionalized plasticizer to improve the physical properties of the composition. In particular, there is an industry need for modified nitrile-group containing elastomers to improve the high temperature and processing properties without adversely affecting the natural elastomer properties and/or the low temperature properties. The compositions described herein satisfy this need.